After two straight months of getting pummeled by Mitt Romney in the race for cash, President Barack Obama’s campaign is stepping up pressure on donors and bundlers to find new money.

Obama’s campaign and its allies are aggressively pushing wealthy and smaller-dollar donors alike to open their wallets after Democrats lagged behind Romney and the Republican National Committee by $35 million in June and about $17 million in May.

The campaign has been firing off email missives aimed at working-class donors, Obama himself has been asking his 2008 big donors to re-up and the campaign is pressuring bundlers to rake in more cash. The search for new donors is a major priority.

“There is a sense of urgency that things are going well but we need to redouble our efforts,” said Don Peebles, a Washington real estate developer who sits on Obama’s national finance committee and is credited with bundling as much as $200,000 for the reelection campaign.

Peebles said there are “constant phone calls and discussions” among finance committee members — including a Monday call in which he did not participate — urging bundlers to pick up the pace. “Trying to find new big donors, that’s one of the big things,” he said.

The problem, he said, is that Obama is alienating potential big donors with attacks on Wall Street while his reelection campaign has already reaped the maximum contributions from its most supportive big donors. So the challenge for Obama bundlers is identifying and courting new donors “because the donors who are predisposed to give to him have already given,” Peebles added.

But some Democrats are concerned that the presidential cash race may have reached a tipping point. While GOP super PACs have been outraising their Democratic counterparts for months, Democrats have taken solace in Obama’s ability to bring in heaps more campaign cash.

If Romney and the Republicans can keep it up, Democrats could fall far behind in the race on both fronts.

The Obama campaign on Monday fired off emails pleading for more cash, even after chalking up its best fundraising month of this campaign in June.

“We could lose if this continues,” warned a blunt email sent by the Obama campaign to supporters on Monday.

“We had our best fundraising month yet, and we still fell about $35 million short. We can win while being outspent — but we need to keep it close,” said the email from Ann Marie Habershaw, the campaign’s chief operating officer. The email then asks for $3 or more to help close the gap. “If we can’t keep the money race close, it becomes that much harder to win in November,” she warned.

Even before the latest numbers were released, Obama urged donors to shell out cash early to defend against an onslaught on the airwaves come November.

On a conference call last month from Air Force One with donors who maxed out to his 2008 campaign but have yet to do so this time around, Obama warned that the May cash deficit could hurt the campaign’s chances to air ads and organize on the ground.

“Last month, the Romney campaign raised $76 million. We raised $60 million,” he said on the conference call, the audio of which was provided to The Daily Beast. That determines “our planning for whether or not we are gonna go on the air in Florida or Ohio or any of these battleground states, how much advertising we buy, what we spend when it comes to organizing teams.”

Another Obama fundraiser said the pressure to bring in more cash has been constant. “There’s still pressure to raise,” that person said. Still, “I think if we were running 15 percent ahead of where we are, … it would still be that way.”

On the Air Force One call, Obama also lamented “the special interests that are financing my opponent’s campaign” and warned: “A few billionaires can’t drown out millions of voices.”

But attacks on Romney’s wealth and that of his supporters — an increasing Democratic tactic — are not going to help coax any new donors to write big checks, warned Peebles.

“It’s certainly not inspiring anybody who is on the fence about supporting Obama to rush to the phone or to the computer to contribute to him, that’s for sure. The inverse may be happening,” Peebles said, asserting such attacks may “tip them over to Romney and the Republicans or to do nothing.”

The Obama campaign insisted that it hasn’t changed its strategy in response to the latest fundraising numbers. “We have set a course from the beginning and we are continuing on that course,” a campaign aide said.

The campaign and other Democrats insist Romney is now reaping the benefits of big donors coalescing around him after a drawn-out primary battle.

After John Kerry secured the nomination for the Democratic ticket in the spring of 2004, he outraised President George W. Bush for several months only to lose on Election Day.

Romney’s swell of support last month was also fueled by the momentous Supreme Court ruling that upheld most of the Obama administration’s signature health care law. The campaign raised more than $4.3 million in the 24 hours following the ruling that boosted Obama and sparked rage on the right.

The RNC insists that outraising the Democrats is the start of a trend.

“Last month, the GOP side outraised the [Obama campaign]/DNC and they called it a onetime fluke…..well it happened again,” RNC spokesman Sean Spicer said Monday in an email.